Bone loss in long-term renal transplantation: histopathology and densitometry analysis

Bone Disease in Chronic Kidney Disease and Kidney Transplant

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) comprises alterations in calcium, phosphorus, parathyroid hormone (PTH), Vitamin D, and fibroblast growth factor-23 (FGF-23) metabolism, abnormalities in bone turnover, mineralization, volume, linear growth or strength, and vascular calcification leading to an increase in bone fractures and vascular disease, which ultimately result in high morbidity and mortality. The bone component of CKD-MBD, referred to as renal osteodystrophy, starts early during the course of CKD as a result of the effects of progressive reduction in kidney function which modify the tight interaction between mineral, hormonal, and other biochemical mediators of cell function that ultimately lead to bone disease. In addition, other factors, such as osteoporosis not apparently dependent on the typical pathophysiologic abnormalities resulting from altered kidney function, may accompany the different varieties of renal osteodystrophy leading to an increment in the risk of bone fracture. After kidney transplantation, these bone alterations and others directly associated or not with changes in kidney function may persist, progress or transform into a different entity due to new pathogenetic mechanisms. With time, these alterations may improve or worsen depending to a large extent on the restoration of kidney function and correction of the metabolic abnormalities developed during the course of CKD. In this paper, we review the bone lesions that occur during both CKD progression and after kidney transplant and analyze the factors involved in their pathogenesis as a means to raise awareness of their complexity and interrelationship.

Kidney Transplantation, Immunosuppression, and Fracture Risk: Clinical and Economic Implications

Rationale & Objective

Disorders of bone and mineral metabolism frequently develop with advanced kidney disease, may be exacerbated by immunosuppression after kidney transplantation, and increase the risk of fractures.

Study Design

Retrospective database study.

Setting & Participants

Kidney-only transplant recipients aged ≥18 years from 2005 to 2016 in the United States captured in US Renal Data System records, which integrate Organ Procurement and Transplantation Network/United Network for Organ Sharing records with Medicare billing claims.

Exposures

Various immunosuppression regimens in the first 3 months after kidney transplantation.

Outcomes

The development of fractures, as ascertained using diagnostic codes on Medicare billing claims.

Analytical Approach

We used multivariable Cox regression with inverse propensity weighting to compare the incidence of fractures >3 months-to-3 years after kidney transplantation associated with various immunosuppression regimens compared to a reference regimen of antithymocyte globulin (TMG) or alemtuzumab (ALEM) with tacrolimus + mycophenolic acid + prednisone using inverse probability treatment weighting.

Results

Overall, fractures were identified in 7.5% of kidney transplant recipients (women, 8.8%; men, 6.7%; age < 55 years, 5.9%; age ≥ 55 years, 9.3%). In time-varying regression, experiencing a fracture was associated with a substantially increased risk of subsequent death within 3 months (adjusted hazard ratio [aHR], 3.06; 95% confidence interval [CI], 2.45-3.81). Fractures were also associated with increased Medicare spending (first year: $5,122; second year: $10,890; third year: $11,083; [P < 0.001]). Induction with TMG or ALEM and the avoidance or early withdrawal of steroids significantly reduced the risk of fractures in younger (aHR, 0.63; 95% CI, 0.54-0.73) and older (aHR, 0.83; 95% CI, 0.74-0.94) patients. The avoidance or early withdrawal of steroids with any induction was associated with a reduced risk of fractures in women.

Limitations

This was a retrospective study which lacked data on immunosuppression levels.

Conclusions

Fractures after kidney transplantation are associated with significantly increased mortality risk and costs. The early avoidance or early withdrawal of steroids after induction with TMG or ALEM reduces the risk of fractures after kidney transplantation and should be considered for patients at high-risk of this complication, including older adults and women.

Hormonal (Im)Balance and Reproductive System’s Disorders in Transplant Recipients—A Review

Simple Summary

Nowadays, the average human life expectancy is increasing. This applies to both healthy and chronically ill people. It is possible due to improvements in technology, living conditions, and better, more accessible medical care. As the number of patients with end-stage organ failure increases and due to great progress in modern transplantology, every year the number of transplantations rises worldwide. Organ transplantation is not only an ultimate form of therapy but also, especially nowadays, a life-saving procedure. Patients who have undergone transplantation need to face the problem of long-term immunosuppressive therapy on a daily basis, which prolongs the proper function of the grafted organ and prevents the development of graft-versus-host disease. On the other hand, numerous side effects are associated with the usage of these medicaments, among these are disturbances in sex-related hormones, therefore influencing fertility.

Abstract

The rising need for treatment of end stage of organ failure results in an increased number of graft recipients yearly. The most commonly transplanted organs are kidney, heart, liver, bone marrow, lung and skin. The procedure of transplantation saves and prolongs the lives of chronically ill patients or at least improves the quality. However, following transplantation recipients must take immunosuppressive drugs on a daily basis. Usually, the immunosuppressive therapy comprises two or three drugs from different groups, as the mechanism of their action varies. Although the benefits of intake of immunosuppressants is undeniable, numerous side effects are associated with them. To different extents, they are neurotoxic, nephrotoxic and may influence the function of the reproductive system. Nowadays, when infertility is an urgent problem even among healthy pairs, transplant recipients face the problem of disturbance in the hypothalamic−pituitary axis. This review will provide an overview of the most common disturbances among the concentration of sex-related hormones in recipients of both sexes at different ages, including sexually immature children, adults of reproductive age as well as elderly women and men. We have also focused on the numerous side effects of immunosuppressive therapy regarding function and morphology of reproductive organs both in males and females. The current review also presents the regimen of immunosuppressive therapy and time since transplantation.

Promoting bone health in children and adolescents following solid organ transplantation

Solid organ transplantation in children and adolescents provides many benefits through improving critical organ function, including better growth, development, cardiovascular status, and quality of life. Unfortunately, bone status may be adversely affected even when overall status is improving, due to issues with pre-existing bone disease as well as medications and nutritional challenges inherent post-transplantation. For all children and adolescents, bone status entering adulthood is a critical determinant of bone health through adulthood. The overall health and bone status of transplant recipients benefits from attention to regular physical activity, good nutrition, adequate calcium, phosphorous, magnesium and vitamin D intake and avoidance/minimization of soda, extra sodium, and obesity. Many immunosuppressive agents, especially glucocorticoids, can adversely affect bone function and development. Minimizing exposure to "bone-toxic" medications is an important part of promoting bone health in children post-transplantation. Existing guidelines detail how regular monitoring of bone status and biochemical markers can help detect bone abnormalities early and facilitate valuable bone-directed interventions. Attention to calcium and vitamin D supplementation, as well as tapering and withdrawing glucocorticoids as early as possible after transplant, can provide best bone outcomes for these children. Dual-energy X-ray absorptiometry can be useful to detect abnormal bone mass and fracture risk in this population and newer bone assessment methods are being evaluated in children at risk for poor bone outcomes. Newer bone therapies being explored in adults with transplants, particularly bisphosphonates and the RANKL inhibitor denosumab, may offer promise for children with low bone mass post-transplantation.

Risk Factors and Management of Osteoporosis Post-Transplant

Bone and mineral disorders are common after organ transplantation. Osteoporosis post transplantation is associated with increased morbidity and mortality. Pathogenesis of bone disorders in this particular sub set of the population is complicated by multiple co-existing factors like preexisting bone disease, Vitamin D deficiency and parathyroid dysfunction. Risk factors include post-transplant immobilization, steroid usage, diabetes mellitus, low body mass index, older age, female sex, smoking, alcohol consumption and a sedentary lifestyle. Immunosuppressive medications post-transplant have a negative impact on outcomes, and further aggravate osteoporotic risk. Management is complex and challenging due to the sub-optimal sensitivity and specificity of non-invasive diagnostic tests, and the underutilization of bone biopsy. In this review, we summarize the prevalence, pathophysiology, diagnostic tests and management of osteoporosis in solid organ and hematopoietic stem cell transplant recipients.

Bone Health in Glomerular Kidney Disease

PURPOSE OF REVIEW

To summarize the literature regarding alterations in bone health in patients with glomerular kidney disease and highlight areas in need of additional investigation.

RECENT FINDINGS

There is mounting evidence that children and adults with glomerular conditions, with or without compromised kidney function, comprise a distinct subgroup of patients with unique risk factors for altered bone health. Patients with glomerular kidney disease are exposed to both disease-related and treatment-related factors that affect bone structure and function. In addition to chronic kidney disease-related risk factors for impaired bone health, high rates of exposure to osteotoxic medications, varying degrees of systemic inflammation, and altered vitamin D metabolism may contribute to compromised bone health in individuals with glomerular disease. Further study is needed to better understand these risk factors and the complex interaction between the immune system and bone cells in glomerular disease.

Mineral and Bone Disease in Kidney Transplant Recipients

PURPOSE OF REVIEW

Despite metabolic improvements following kidney transplantation, transplant recipients still often suffer from complex mineral and bone disease after transplantation.

RECENT FINDINGS

The pathophysiology of post-transplant disease is unique, secondary to underlying pre-transplant mineral and bone disease, immunosuppression, and changing kidney function. Changes in modern immunosuppression regimens continue to alter the clinical picture. Modern management includes reducing cumulative steroid exposure and correcting the biochemical abnormalities in mineral metabolism. While bone mineral density screening appears to help predict fracture risk and anti-osteoporotic therapy appears to have a positive effect on bone mineral density, more data regarding specific treatment is necessary. Patients with mineral and bone disease after kidney transplantation require special care in order to properly manage and mitigate their mineral and bone disease. Recent changes in clinical management of transplant patients may also be changing the implications on patients' mineral and bone disease.

Mineral and Bone Disorders After Kidney Transplantation

The risk of mineral and bone disorders among patients with chronic kidney disease is substantially elevated, owing largely to alterations in calcium, phosphorus, vitamin D, parathyroid hormone, and fibroblast growth factor 23. The interwoven relationship among these minerals and hormones results in maladaptive responses that are differentially affected by the process of kidney transplantation. Interpretation of conventional labs, imaging, and other fracture risk assessment tools are not standardized in the post-transplant setting. Post-transplant bone disease is not uniformly improved and considerable variation exists in monitoring and treatment practices. A spectrum of abnormalities such as hypophosphatemia, hypercalcemia, hyperparathyroidism, osteomalacia, osteopenia, and osteoporosis are commonly encountered in the post-transplant period. Thus, reducing fracture risk and other bone-related complications requires recognition of these abnormalities along with the risk incurred by concomitant immunosuppression use. As kidney transplant recipients continue to age, the drivers of bone disease vary throughout the post-transplant period among persistent hyperparathyroidism, de novo hyperparathyroidism, and osteoporosis. The use of anti-resorptive therapies require understanding of different options and the clinical scenarios that warrant their use. With limited studies underscoring clinical events such as fractures, expert understanding of MBD physiology, and surrogate marker interpretation is needed to determine ideal and individualized therapy.

Evolution of bone disease after kidney transplantation: A prospective histomorphometric analysis of trabecular and cortical bone

AIM

Post-transplant bone disease results from multiple factors, including previous bone and mineral metabolism disturbances and effects from transplant-related medications. Bone biopsy remains the gold-standard diagnostic tool.

METHODS

We aimed to prospectively evaluate trabecular and cortical bone by histomorphometry after kidney transplantation. Seven patients, willing to perform follow-up bone biopsy, were included in the study. Dual-X-ray absorptiometry and trans-iliac bone biopsy were performed within the first 2 months after renal transplantation and repeated after 2-5 years of follow-up.

RESULTS

Follow-up biopsy revealed a significant decrease in osteoblast surface/bone surface (0.91 ± 0.81 to 0.47 ± 0.12%, P = 0.036), osteoblasts number/bone surface (0.45 (0.23, 0.94) to 0.00/mm(2) , P = 0.018) and erosion surface/bone surface (3.75 ± 2.02 to 2.22 ± 1.38%, P = 0.044). A decrease in trabecular number (3.55 (1.81, 2.89) to 1.55/mm (1.24, 2.06), P = 0.018) and increase in trabecular separation (351.65 ± 135.04 to 541.79 ± 151.91 μm, P = 0.024) in follow-up biopsy suggest loss in bone quantity. We found no significant differences in cortical analysis, except a reduction in external cortical osteonal eroded surface (5.76 (2.94, 13.97) to 3.29% (0.00, 6.67), P = 0.043). Correlations between bone histomorphometric and dual-X-ray absorptiometry parameters gave inconsistent results.

CONCLUSIONS

The results show a reduction in bone activity, suggesting increased risk of adynamic bone and loss of bone volume. Cortical bone seems less affected by post-transplant biological changes in the first years after kidney transplantation.

The Effect of Cyclosporin A on Alveolar Bone in Rats Subjected to Experimental Periodontal Disease

Cyclosporine A (CsA), broadly used in organ transplantation, may contribute to pathogenesis of osteoporosis. The aim of this study was to investigate the effects of CsA on alveolar bone in rats subjected or not to experimental periodontal disease using biochemical, radiographic, and histometric analysis. Forty Wistar rats were divided into 4 equal groups: Group I (Control), Group II (CsA was injected subcutaneously in a daily dose of 10 mg/kg), Group III (Ligature was placed around the mandibular molars), Group IV (Ligature+CsA). After 60 days, rats were decapitated, serum alkaline phosphatase and calcium levels were measured. Radiographic-alveolar bone loss (ABL), histometric-ABL, and percentage of new alveolar bone formation (NABF%) were determined on mandibular molars. Significant increase in serum alkaline phosphatase levels ( p < 0.001), no significant difference in calcium levels were observed ( p > 0.05) in Group IV compared to Group III. Radiographic and histometric-ABL were significantly less ( p < 0.001), NABF% was significantly greater ( p < 0.05) in Group IV than in Group III. No significant difference in any of the parameters between Group II and Group I was found. It can be concluded that in the presence of periodontal disease, CsA treatment may bring out an imbalance in the alveolar bone homeostasis by decreasing resorption and stimulating formation of alveolar bone in rats.

Metabolic Bone Disease in the Post-transplant Population: Preventative and Therapeutic Measures

Post-transplant bone disease contributes significantly to patients' morbidity and mortality after transplantation and has an impact on their quality of life. This article discusses the major contributors to mechanisms causing bone loss, highlighting the role of preexisting disease in both kidney and liver failure and contributions from glucocorticoids and calcineurin inhibitors. Suggested monitoring and investigations are reviewed as well as treatment as far as the current literature supports, emphasizing the difference between kidney and liver recipients.

Bone disease in post-transplant patients

PURPOSE OF REVIEW

Mineral and bone disorders are common problems in organ transplant recipients. Successful transplantation solves many aspects of abnormal mineral and bone metabolism, but the degree of improvement is frequently incomplete. Posttransplant bone disease can affect long-term outcomes as well as increase the likelihood of fracture. In this article, we reviewed the major posttransplant bone diseases and recent advances in treatment strategies.

RECENT FINDINGS

Pretransplant bone disease and immunosuppressants are important risk factors for posttransplant bone disease. Corticosteroid withdrawal may result in minimal or no protection against fractures, with increased risk for acute rejection. Vitamin D analogue and bisphosphonate are frequently used to prevent and treat posttransplant osteoporosis. Posttransplant hyperparathyroidism increases the risk for all-cause mortality and graft loss, but not major cardiovascular events. Cinacalcet was well tolerated and effectively controlled hypercalcemic hyperparathyroidism; however, it did not improve bone mineral density and discontinuation led to parathyroid hormone rebound. Six-month paricalcitol supplementation reduced parathyroid hormone levels and attenuated bone remodeling and mineral loss in case of posttransplant hyperparathyroidism.

SUMMARY

Posttransplant bone diseases present in various forms, including osteoporosis, hyperparathyroidism, adynamic bone disease, and osteonecrosis. Prophylactic and therapeutic approaches to both pretransplant and posttransplant periods should be considered.

Current Status of Research on Osteoporosis after Solid Organ Transplantation: Pathogenesis and Management

Improved survival following organ transplantation has brought to the forefront some long-term complications, among which osteoporosis and associated fractures are the major ones that adversely affect the quality of life in recipients. The pathogenesis of osteoporosis in transplant recipients is complex and multifactorial which may be related to increased bone resorption, decreased bone formation, or both. Studies have shown that the preexisting underlying metabolic bone disorders and the use of immunosuppressive agents are the major risk factors for osteoporosis and fractures after organ transplantation. And rapid bone loss usually occurs in the first 6–12 months with a significant increase in fracture risk. This paper will provide an updated review on the possible pathogenesis of posttransplant osteoporosis and fractures, the natural history, and the current prevention and treatment strategies concerning different types of organ transplantation.

Bone metabolism and arterial stiffness after renal transplantation

BACKGROUND/AIMS

To assess the relationship between bone and vascular disease and its changes over time after renal transplantation. Metabolic bone disease (MBD) is common in chronic kidney disease (CKD) and is associated with cardiovascular (CV) disease. Following transplantation (Tx), improvement in CV disease has been reported; however, data regarding changes in bone disease remain controversial.

METHODS

Bone turnover and arterial stiffness (pulse wave velocity (PWV)) were assessed in 47 Tx patients (38 (3-191) months after Tx).

RESULTS

Bone alkaline phosphatase (BALP), osteocalcin (OC) and beta-crosslaps were significantly higher in Tx patients, and decreased significantly after one year. There was a negative correlation between BALP, OC and steroid administered (r = -0.35; r = -0.36 respectively). PWV increased in the Tx group (1.15 SD). In patients with a follow up of <24 months, PWV was correlated with BALP and beta-crosslaps (r=0.53; r = 0.69 respectively) while in the ≥24 months group, PWV was correlated with cholesterol (r=0.38).

CONCLUSIONS

Increased bone turnover and arterial stiffness are present following kidney transplantation. While bone turnover decreases with time, arterial stiffness correlates initially with bone turnover, after which the influence of cholesterol becomes significant. Non-invasive estimation of bone metabolism and arterial stiffness may help to assess CKD-MBD following renal transplantation.

Osteoporosis after renal transplantation

Bone loss and fracture are serious sequelae of kidney transplantation, associated with morbidity, mortality and high economic costs. The pathogenesis of post-transplantation bone loss is multifactorial and complex. Pre-existing bone mineral disease is responsible for a significant part, but it is aggravated by risk factors emerging after renal transplantation with immunosuppressive agents being one of the key contributors. The decrease in bone mass is particularly prominent during the first 6-12 months after transplantation, continuing at a lower rate thereafter. Bone mineral density measurements do not predict bone histology and bone biopsy findings reveal heterogeneous lesions, which vary according to time after transplantation. Currently, vitamin D and bisphosphonates are the most extensively tested therapeutic agents against this accelerated bone loss in renal transplant recipients. Both of these agents have proven effective, but there is no evidence that they decrease fracture risk. More studies are needed to examine the complex pathophysiologic mechanisms implicated in this population, as well as the effects of different therapeutic interventions on bone disorders after kidney transplantation.

[Mineral and bone disorders in renal transplantation]

The deregulation of bone and mineral metabolism during chronic kidney disease (CKD) is a daily challenge for physicians, its management aiming at decreasing the risk of both fractures and vascular calcifications. Renal transplantation in the context of CKD, with pre-existing renal osteodystrophy as well as nutritional impairment, chronic inflammation, hypogonadism and corticosteroids exposure, represents a major risk factor for bone impairment in the post-transplant period. The aim of this review is therefore to provide an update on the pathophysiology of mineral and bone disorders after renal transplantation.

Renale osteodystrophie

The incidence of renal osteodystrophy (ROD) increases with deteriorating kidney function, affecting virtually every patient on chronic dialysis treatment. ROD can persist after kidney transplantation and may be aggravated by immunosuppressants, mainly glucocorticoids. Fracture risk, including hip fractures, is markedly elevated in patients with renal disease compared to the general population. Depending on the type of ROD, high or low bone turnover can be found. Because of poor positive and negative predictive values of serological markers of bone turnover and limited technical capabilities of various bone imaging modalities, the only reliable method to correctly classify ROD is the transiliac bone biopsy. Elevated bone turnover can be successfully treated with active vitamin D, cinacalcet, or parathyreoidectomy, but all of these therapies may lead to oversuppression of bone metabolism. Currently, no specific therapy is available for low turnover bone disease. Bisphosphonates can be a therapeutic option for selected patients after renal transplantation.

Pancreas-kidney transplantation is associated with reduced fracture risk compared with kidney-alone transplantation in men with type 1 diabetes

Both type 1 diabetes mellitus and end stage renal disease are associated with increased fracture risk, likely due to metabolic abnormalities that reduce bone strength. Simultaneous pancreas-kidney transplantation is a treatment of choice for patients with both disorders, yet the effects of simultaneous pancreas-kidney versus kidney transplantation alone on post-transplantation fracture risk are unknown. From the United States Renal Data System we identified 11, 145 adults with type 1 diabetes undergoing transplantation of whom 4,933 had a simultaneous pancreas-kidney while 6, 212 had a kidney alone transplant between 2000 and 2006. Post-transplantation fractures resulting in hospitalization were identified from discharge codes. Time to first fracture was modeled and propensity score adjustment was used to balance covariates between groups. Fractures occurred in significantly fewer (4.7%) of pancreas-kidney compared to kidney-alone transplant (5.9%) cohorts. After gender stratification and adjustment for fracture covariates, pancreas-kidney transplantation was associated with a significant 31% reduction in fracture risk in men (hazard risk 0.69). Older age, white race, prior dialysis and pre transplantation fracture were also associated with increased fracture risk. Prospective studies are needed to determine the gender-specific mechanisms by which pancreas-kidney transplantation reduces fracture risk in men.

CKD-mineral and bone disorder management in kidney transplant recipients

Kidney transplantation, the most effective treatment for the metabolic abnormalities of chronic kidney disease (CKD), only partially corrects CKD-mineral and bone disorders. Posttransplantation bone disease, one of the major complications of kidney transplantation, is characterized by accelerated loss of bone mineral density and increased risk of fractures and osteonecrosis. The pathogenesis of posttransplantation bone disease is multifactorial and includes the persistent manifestations of pretransplantation CKD-mineral and bone disorder, peritransplantation changes in the fibroblast growth factor 23-parathyroid hormone-vitamin D axis, metabolic perturbations such as persistent hypophosphatemia and hypercalcemia, and the effects of immunosuppressive therapies. Posttransplantation fractures occur more commonly at peripheral than central sites. Although there is significant loss of bone density after transplantation, the evidence linking posttransplantation bone loss and subsequent fracture risk is circumstantial. Presently, there are no prospective clinical trials that define the optimal therapy for posttransplantation bone disease. Combined pharmacologic therapy that targets multiple components of the disordered pathways has been used. Although bisphosphonate or calcitriol therapy can preserve bone mineral density after transplantation, there is no evidence that these agents decrease fracture risk. Moreover, bisphosphonates pose potential risks for adynamic bone disease.

Management of mineral and bone disorder after kidney transplantation

PURPOSE OF REVIEW

Mineral and bone disorders (MBDs), inherent complications of moderate and advanced chronic kidney disease, occur frequently in kidney transplant recipients. However, much confusion exists about the clinical application of diagnostic tools and preventive or treatment strategies to correct bone loss or mineral disarrays in transplanted patients. We have reviewed the recent evidence about prevalence and consequences of MBD in kidney transplant recipients and examined diagnostic, preventive and therapeutic options to this end.

RECENT FINDINGS

Low turnover bone disease occurs more frequently after kidney transplantation according to bone biopsy studies. The risk of fracture is high, especially in the first several months after kidney transplantation. Alterations in minerals (calcium, phosphorus and magnesium) and biomarkers of bone metabolism (parathyroid hormone, alkaline phosphatase, vitamin D and FGF-23) are observed with varying impact on posttransplant outcomes. Calcineurin inhibitors are linked to osteoporosis, whereas steroid therapy may lead to both osteoporosis and varying degrees of osteonecrosis. Sirolimus and everolimus might have a bearing on osteoblast proliferation and differentiation or decreasing osteoclast-mediated bone resorption. Selected pharmacologic interventions for the treatment of MBD in transplant patients include steroid withdrawal, and the use of bisphosphonates, vitamin D derivatives, calcimimetics, teriparatide, calcitonin and denosumab.

SUMMARY

MBD following kidney transplantation is common and characterized by loss of bone volume and mineralization abnormalities, often leading to low turnover bone disease. Although there are no well established therapeutic approaches for management of MBD in renal transplant recipients, clinicians should continue individualizing therapy as needed.

Gender- and dose-related effects of cyclosporin A on hepatic and bone metabolism

Previous data have shown gender-related differences in the skeletal effects of the immunosuppressive drug cyclosporin A (CsA) in rats. To test the hypothesis that the gender-related skeletal effects of CsA are caused by gender-specific metabolism of this drug, we treated aged male and female sham-operated, gonadectomized (GX) as well as sex hormone-supplemented GX rats with 5 mg/kg CsA three times per week for 2 months, and analyzed the bone phenotype as well as the concentrations of CsA and its major metabolites AM1, AM1c, AM9, and AM4N in blood, urine, and liver tissue. CsA treatment induced high turnover osteopenia in males, but not females. Male rats showed several-fold higher CsA and CsA metabolite blood levels compared with females. Renal clearance data revealed that CsA undergoes selective tubular reabsorption in male, but not female rats. However, a mathematical modeling approach demonstrated that the higher CsA blood levels in males were almost exclusively caused by a 6-fold lower hepatic clearance rate compared with females. In addition, we subcutaneously treated female rats with up to 6-fold higher doses of CsA. Similar to males, high dose CsA induced high turnover osteopenia in female rats. Our data show that the gender-related differences in the skeletal effects of CsA are caused by a higher hepatic clearance rate for CsA in female compared to male rats, and not by a differential skeletal response to CsA. Moreover, our study indicates that CsA blood levels of ≤200 ng/ml measured by HPLC do not induce high turnover osteopenia in aged rats.

Bone mineral disorders in pediatric and adolescent renal transplant recipients

Incomplete resolution of abnormalities of mineral metabolism associated with CRF results in the relatively high prevalence of ROD in pediatric kidney recipients. This non-randomized, cross-sectional, and analytic-descriptive study on bone density, vitamin D, and mineral metabolism was performed in 57 children and adolescents who had received a total of 60 renal allografts in Shiraz, Iran. The height and weight of the patients were measured; their serum calcium (Ca), phosphorus (P), Alk-P, PTH, 25(OH)-vitamin D(3), BUN, creatinine, and electrolyte levels were analyzed, and a complete blood count was performed. In addition, standard radiologic bone assessments, which included conventional left hand-wrist radiography and bone mineral densitometry by the DXA technique, were carried out. Special pediatric software was used for age-related interpretation of the Z-scores of BMD. SPSS(®) software (version 15) was used for statistical analyses. We studied 57 patients (27 males [47.4%]) with a mean age of 18.7 ± 4.25 (9-27) yr and a mean age at transplantation of 13.1 ± 3.46 (4.5-20) yr. They had a post-transplantation follow-up of 67.1 ± 33.8 (6-132) months, and all had well-functioning allografts at enrollment. The mean height age of the patients was 11.9 ± 1.8 (6-15.5), and the mean bone age was 15.6 ± 3.3 (7-19) yr, which corresponded to mean height-age and bone-age retardations of 5.7 ± 2.3 (0.5-10.5) and 1.22 ± 1.47 (0-7) yr, respectively. Hyperphosphatemia and hypercalcemia were each found in nine patients (15.8%), hypophosphatemia in five (8.8%), and hypocalcemia in none of the patients. Seven out of 57 patients (12.3%) had a (Ca×P) product of more than 55 mg(2)/dL(2). Hyperparathyroidism was found in 27 (47.3%) and vitamin D(3) deficiency in four (7%) of the cases. The serum level of Alk-P was higher than the age-related normal range in 20 patients (35%). Left hand-wrist radiography showed no radiologic sign of ROD in any patient. The mean BMD Z-score was -1.77 ± 1.13 (-4.2-1.1) for the lumbar spine and -1.64 ± 0.89 (-3.9 to 1.9) for the femoral neck. "Stepwise backward regression" revealed a significant inverse correlation between the serum level of PTH and the GFR of the transplanted kidney; this correlation was independent from the influence of other variables such as Ca, P, and Alk-P (p = 0.011, β = -1.556). Bone age and height age both showed significant correlations with age at transplantation and serum levels of P (p < 0.001), but only bone age had a meaningful correlation with Alk-P (p = 0.036). The BMD Z-scores showed statistically meaningful correlations with the serum level of Alk-P, which were independent from the influence of other variables such as Ca, P, and PTH (p ≤ 0.002). Our study revealed a relatively high prevalence of bone mineral disorder in pediatric kidney recipients, which suggests the need for a routine program for periodic screening of these patients to facilitate early diagnosis of either persistent or evolving manifestations of disturbed mineral metabolism, especially ROD.

Evaluation of the Effect of Ozonated Plant Oils on the Quality of Osseointegration of Dental Implants Under the Influence of Cyclosporin A: An In Vivo Study

Immunosuppressive agents have been recognized as factors that induce changes and modifications in bone metabolism. The purpose of this study was to evaluate the effect of ozonated plant extracts (herein termed ozonated oil) under the influence of Cyclosporin A (CsA) on osseointegration. A total of 20 dental implants were placed in 20 rabbit tibiae assigned to Group A or B. CsA was injected at an immunosuppressive dose in Groups A and B as a single-dose treatment. At the day of surgery, Group A received a single topical ozonated oil treatment (0.55 mL) around dental implants; Group B, the control group, received no ozonated oil. Animals were sacrificed after 8 weeks. Radiographs were obtained at implant surgery and on the day of sacrifice. Bone quality was compared between the 2 groups. Radiographically, osseointegration was microscopically evaluated using scanning electron and light microscopies. In ozonated Group A specimens, light microscopic examination demonstrated evidence of more organized mature bone compared with Group B. Within the limits of this study, the results suggest that short-term administration of CsA, when administered with topical ozonated oil, may influence bone density and the quality of dental implant osseointegration. Therefore, topically applied ozonated oil may influence bone density and the quality of osseointegration around dental implants.

Loss of bone mineral density in renal transplantation recipients

AIM

This study investigated the prevalence and contributing factors of loss of bone mineral density after renal transplantation among Turkish patients.

PATIENTS AND METHODS

The study included 70 subjects, namely 50 males and 20 females of overall mean age of 36.94 ± 10.09 years. We measured femoral neck mineral density by dual-energy X-ray absorptiometry (DEXA). A T score above -1 was defined as a normal bone mineral density compared with T scores of -1.0 to -2.5 or below -2.5 which were defined as either osteopenia or osteoporosis, respectively.

RESULTS

At a median duration of 23 months after renal transplantation, osteopenia or osteoporosis was observed among 30 (42.9%) or 30 (42.9%) of the 70 patients, respectively. The mean body mass index (BMI) value was significantly higher among the normal than the osteoporotic group: 27.59 ± 4.66 kg/m(2) vs 24.18 ± 3.57 kg/m(2), respectively. However, no significant differences occurred in terms of BMI among the other groups. The amount of proteinuria was significantly lower in the normal than the osteopenic or osteoporotic group: (12.5 (range, 10.0-20.0); 105.0 (10.0-2800.0) or 215.5 (10.0-1880.0) mg/d (P = .001 and .004, respectively). In contrast, there was no significant difference between the amounts of proteinuria displayed by the osteopenic group and the osteoporotic group (P < .05)]. These patient groups showed no difference in age, gender, donor source, cause of end-stage renal disease (ESRD), pretransplant dialysis modality, duration of dialysis, use of a vitamin D preparation, immunosuppressive regimen, posttransplantation period, levels of iPTH or 25 hydroxy vitamin D3 (25OH vit D), exposure to tacrolimus or cyclosporine (CyA), calcium × phosphate product, serum albumin and hemoglobin content, creatinine clearance, or serum bicarbonate concentrations (P > .05). The T scores of the femoral neck correlated with BMI (r: 0.415; P = .001), 25OH vit D level (r: 0.268, P = .026), creatinine clearance (r: 0.273, P = .022), and serum glucose level (r: 0.349, P = .003). It inversely correlated with the amount of proteinuria (r: -0.263, P = .028), serum alkaline phosphatase level (r: -0.329, P = .005), and serum magnesium concentration (r: -0.252, P = .035). Upon multivariate analysis, BMI and 25OH vit D level were observed to be independent risk factors for loss of femoral mineral density.

CONCLUSION

Loss of bone mineral density is a common complication that correlates with low BMI values and decreased 25OH vit D levels as major risk factors for this problem.

[Bone mineral density in patients with renal hyperparathyroidism undergoing surgery: relationship with bone parameters]

BACKGROUND AND OBJECTIVES

Hyperparathyroidism (HPT) in chronic kidney disease (CKD) may alter the composition and bone architecture, and cause fractures. The DEXA bone mineral density (BMD), used to predict fracture risk, measures the amount of calcium in bone. However, we do not know the relationship between BMD and bone composition.

PATIENT AND METHOD

Our study, conducted in two groups of renal patients with HPT who underwent parathyroidectomy (PTX): patients on hemodialysis (HD group) and patients with renal transplant (RT group). The aims were to quantify and value the differences among groups and by gender on bone mineral density, quantify and define differences between these two groups and a control group regarding the elemental composition of bone marrow biopsy obtained and static parameters of bone histomorphometry, and define a possible relationship between bone mineral density and bone elements versus histomorphometric parameters.

RESULTS

The BMD mean in femur was higher in TR group than in HD group. Linear correlation analysis performed between parameters versus BMD and bone histomorphometry elements, considering both TR and HD, only correlation between femur BMD (gr/cm2) and calcium (r=0.435, p=0.034, n=24) was observed.

CONCLUSION

Hyperparathyroidism patients undergoing renal transplant had better femoral BMD than those on hemodialysis; the trabecular volume was lower in kidney transplantation, while the volume of fibrosis was higher in hemodialysis patients; the elements in bone transplant and hemodialysis were in similar proportion, while the calcium content tended to be higher in renal transplant.

Skeletal sequelae of cancer and cancer treatment

INTRODUCTION

Survivors of cancer may experience lingering adverse skeletal effects such as osteoporosis and osteomalacia. Skeletal disorders are often associated with advancing age, but these effects can be exacerbated by exposure to cancer and its treatment. This review will explore the cancer and cancer treatment-related causes of skeletal disorders.

METHODS

We performed a comprehensive search, using various Internet-based medical search engines such as PubMed, Medline Plus, Scopus, and Google Scholar, for published articles on the skeletal effects of cancer and cancer therapies.

RESULTS

One-hundred-forty-two publications, including journal articles, books, and book chapters, met the inclusion criteria. They included case reports, literature reviews, systematic analyses, and cohort reports. Skeletal effects resulting from cancer and cancer therapies, including hypogonadism, androgen deprivation therapy, estrogen suppression, glucocorticoids/corticosteroids, methotrexate, megestrol acetate, platinum compounds, cyclophosphamide, doxorubicin, interferon-alpha, valproic acid, cyclosporine, vitamin A, NSAIDS, estramustine, ifosfamide, radiotherapy, and combined chemotherapeutic regimens, were identified and described. Skeletal effects of hyperparathyroidism, vitamin D deficiency, gastrectomy, hypophosphatemia, and hyperprolactinemia resulting from cancer therapies were also described.

DISCUSSION/CONCLUSIONS

The publications researched during this review both highlight and emphasize the association between cancer therapies, including chemotherapy and radiotherapy, and skeletal dysfunction.

IMPLICATIONS FOR CANCER SURVIVORS

These studies confirm that cancer survivors experience a more rapid acceleration of bone loss than their age-matched peers who were never diagnosed with cancer. Further studies are needed to better address the skeletal needs of cancer survivors.

Evaluation and management of bone disease and fractures post transplant

Bone disease is common in recipients of kidney, liver, heart, and lung transplants and results in fractures in 20-40% of patients, a rate much higher than expected for age. Fractures occur because of the presence of bone disease as well as other factors such as neuropathy, poor balance, inactivity, and low body or muscle mass. Major contributors to bone disease include both preexisting bone disease and bone loss post transplant, which is greatest in the first 6-12 months when steroid doses are highest. Bone disease in kidney transplant recipients should be considered different from that which occurs in other solid organ transplant recipients for several reasons including the presence of renal osteodystrophy, which contributes to low bone mineral density in these patients; the location of fractures (more common in the legs and feet in these patients than in spine and hips as in other solid organ recipients); and the potential danger in using bisphosphonate therapy, which may cause more harm than good in kidney transplant recipients with low bone turnover. Evaluation in all patients should preferably occur in the pretransplant period or early post transplant and should include assessment of fracture risk as well as metabolic factors that can contribute to bone disease. Bone mineral density measurement is recommended in all patients even if its predictive value for fracture risk in the transplant population is unproven. Management of bone disease should be directed toward decreasing fracture risk as well as improving bone density. Pharmacologic and nonpharmacologic treatment strategies are discussed in this review. Although there have been many studies describing a beneficial effect of bisphosphonates and vitamin D analogues on bone density, none have been powered to detect a decrease in fracture rate.

Calcium and bone metabolism pre- and post-kidney transplantation

Chronic kidney disease (CKD) is associated with significant disturbances in bone and mineral metabolism, the manifestations of which are heterogeneous in their expression and clinical impact. Over the last 2 decades, advances in the management of CKD and improved outcomes of kidney transplantation have led to the emergence of post-transplantation bone disease as a serious cause of morbidity in long-term survivors. The management of post-kidney transplantation bone disease represents a difficult challenge because of its complex pathophysiology and the paucity of clinical data on effective therapies. The optimal management of disturbances of bone and mineral metabolism before kidney transplantation forms the cornerstone of their successful management after transplantation. Therapeutic strategies to effectively and safely decrease skeletal morbidity after kidney transplantation are not yet clearly established.

Low-turnover bone disease in hypercalcemic hyperparathyroidism after kidney transplantation

Hypercalcemia in persistent secondary hyperparathyroidism after kidney transplantation is considered to result from increased bone resorption. Bone biopsies' studies, however, have never been performed in these patients. Bone biopsies after double tetracycline labeling were obtained from 17 patients with hypercalcemic hyperparathyroidism and an estimated glomerular filtration rate > 30 mL/min/1.73 m2. Serologic bone markers, calcitriol, intact fibroblast growth factor-23 (iFGF-23), and serum and 24h urine concentration of calcium and phosphate were measured in all patients. Tubular maximum for phosphate corrected for GFR (TmP/GFR), and the fractional excretion of calcium (FeCa) were calculated. High-turnover renal osteodystrophy (ROD) was present in nine and low-turnover ROD in eight patients. The bone formation rate was significantly associated with bone alkaline phosphatase, c-telopeptide and osteocalcin. In patients with high turnover ROD, osteocalcin was also significantly higher than in patients with decreased bone formation. The FeCa was normal or below normal in 14/17 patients. TmP/GFR was below normal in all patients. Neither intact PTH nor iFGF-23 was associated with TmP/GFR, FeCa or any histomorphometric bone parameter. We conclude that hypercalcemia of posttransplant hyperparathyroidism can be associated with high or low turnover bone disease. Decreased calcium excretion suggests an additive tubular effect on hypercalcemia.

Bone disease after renal transplantation

It has been well established that a rapid decrease in bone mineral density (BMD) occurs in the first 6 to 12 mo after a successful renal transplantation and persists, albeit at a lower rate, for many years. This rapid BMD loss significantly increases the fracture risk of these patients to levels that are even higher than those of patients who have chronic kidney disease stage 5 and are on dialysis. The presence of low BMD in renal transplant patients as a predictor of risk fracture is controversial. Indeed, as has been suggested also for patients with postmenopausal osteoporosis, there is not a compelling correlation between the decline in BMD and skeletal fractures. However, bone disease after renal transplantation probably represents a unique bone disorder that must encompass underlying renal osteodystrophy. In fact, this syndrome results from multiple factors that include pretransplantation bone status, use of glucocorticoids and other immunosuppressive drugs, hypophosphatemia, and alterations of the calcium-vitamin D axis. Recent studies have demonstrated decreased osteoblast number, reduced bone formation rate, delayed mineralization, and increased osteoblast and osteocyte apoptosis. Bisphosphonates and vitamin D metabolites may be valuable in preventing or diminishing early bone loss. However, clinicians should be careful with the use of bisphosphonates and oversuppression of bone, especially in patients with low bone turnover. New prospective, controlled trials are required to confirm the real efficacy of these drugs, particularly in long-term renal transplant patients.

Effect of kidney transplantation on bone

A broad range of different factors aggravates renal osteodystrophy, which is present in virtually all patients with chronic kidney disease and after successful kidney transplantation. Altered hormonal status, including sex hormones and parathyroid hormone (PTH), a deficit of 1,25(OH)(2) vitamin D(3) (calcitriol), immunosuppressive therapy and post-operative immobilization contribute to a progressive loss of bone density and structure. The decrease of bone mass is particularly prominent during the first 6 months after kidney transplantation and is associated with an increased number of fractures, both compared with the normal population as well as with dialysis patients. At particular risk are patients with a history of diabetes, long duration of haemodialysis and post-menopausal women. To prevent post-transplant bone loss prescription of steroids should be minimized and withdrawn as early as possible. Additional intake of alpha-calcidol [25(OH) vitamin D(3)] or calcitriol, despite normal serum levels, reduces persistent hyperparathyroidism after kidney transplantation, improves intestinal calcium absorption and activates osteoblasts. Inhibition of osteoclasts by biphosphonate therapy seems to effectively reverse bone loss during the early and late course of kidney transplantation. However, as the majority of transplant recipients have a low-turnover bone disease, inhibition of osteoclasts, through which bone turnover is impaired, might further reduce osteoblast activity and promote osteoid synthesis. Most investigations were small-scale studies with 10-100 participants and a follow up of only 12 months. This makes conclusions on the effect of any intervention on the fracture rate impossible. Larger, randomized multicentre studies investigating bone-sparing therapy on hard end points are therefore advocated.

Effects of tacrolimus, cyclosporin A and sirolimus on MG63 cells

The reduction in bone mineral density after organ transplantation results in increased morbidity (post-transplantation bone disease) and remains an unsolved problem. A connection with the long-term application of nonglucocorticoidal immunosuppressants is the subject of controversial discussion. We hypothesized that such substances have an influence on the skeletal system on the cellular level by modulating osteoblast differentiation. Therefore, we investigated the effects of tacrolimus, cyclosporin A and sirolimus as representative substances of nonglucocorticoidal immunosuppressants on cell proliferation and expression of bone tissue-specific genes of human osteoblasts (MG63). None of the examined substances affected cell proliferation, but all influenced the gene expression pattern towards change in cell differentiation. In detail, collagen III and XII, matrix metalloproteinase 2, SMAD2, epithelial growth factor receptor, annexin V and osteonectin expression were increased by all of the examined substances. Tacrolimus, cyclosporin A and sirolimus influence intracellular signalling pathways, transmembranous receptors and bone-specific matrix synthesis. They do not have antiproliferative or toxic effects. We postulate that the shown changes of osteoblast differentiation cause post-transplantation disease.

Bone disease in long-term renal transplant recipients with severe osteopenia: a cross-sectional study

BACKGROUND

Fracture is a disabling clinical outcome after transplantation, but there is little histopathological information on long-term renal recipients with severe osteopenia.

METHODS

Twenty kidney recipients (8.3+/-1.9 years after transplantation), 13 males and 7 females (five postmenopausal) with nearly normal renal function, affected by severe osteopenia (T-score: males= -4.9+/-0.28; females= -5.08+/-0.47) underwent bone biopsy and morphometric X-ray absorptiometry to evaluate vertebral fractures.

RESULTS

Histopathological diagnosis was osteoporosis-osteopenia in seven patients, osteitis fibrosa in six, prevalent osteomalacic lesion in six, and "normal" bone in one patient. Significant increases in osteoid volume (OV/BV), osteoid surface, osteoblastic surface (ObS/BS) and osteoid thickness were observed. OV/BV and Obs/BS ratios were inversely correlated to cumulative doses of MPRED (r2=0.85 P<.0001 for both ratios), whereas age, sex, time after transplantation, iPTH levels, and cumulative cyclosporine A dose were not related to osteoblastic indices. Osteoclast surface was slightly increased. Widened mineralization lag times were observed, with normalcy of the bone formation rate. Half of the patients showed fractured vertebrae. No differences in T scores were found when patients were subdivided into groups "with" or "without" vertebral fractures. A higher prevalence of fractures was observed in patients with osteoporosis-osteopenia compared to other osteopathies (P<0.02). No relationships between bone volume versus T-scores were observed.

CONCLUSIONS

In long-term renal transplant recipients, severe osteopenia does not predict osteoporosis alone. The main abnormality we found was an increase in osteoblastic activity with a slight mineralization defect. The heterogeneous bone illness we observed would suggest performing bone biopsy in these patients.

Evolution of bone and plasma concentration of lanthanum in dialysis patients before, during 1 year of treatment with lanthanum carbonate and after 2 years of follow-up

BACKGROUND

Lanthanum carbonate (LC) has been proposed as a new phosphate binder. Presented here are the results from one centre that participated in a multicentre trial to assess the effect of treatment with LC and calcium carbonate (CC) on the evolution of renal osteodystrophy in dialysis patients. Bone biopsies were performed at baseline, after 1 year of treatment and after a further 2-year follow-up period to assess the lanthanum concentration in bone and plasma.

METHODS

Twenty new dialysis patients were randomized to receive LC (median dose 1250 mg) for 1 year (n = 10), followed by 2 years of CC treatment or CC (n = 10) during the whole study period (3 years).

RESULTS

After 36 weeks of treatment, steady state was reached with plasma lanthanum levels varying around 0.6 ng/ml. Six weeks after cessation of 1 year of treatment, the plasma lanthanum levels declined to a value of 0.17 +/- 0.12 ng/ml (P < 0.05) and after 2 years to 0.09 +/- 0.03 ng/ml. Plasma and bone lanthanum levels did not correlate with the average lanthanum dose at any time point. The mean bone concentration in patients receiving LC increased from 0.05 +/- 0.03 to 2.3 +/- 1.6 microg/g (P < 0.05) after 1 year and slightly decreased at the end of the study to 1.9 +/- 1.6 microg/g (P < 0.05).

CONCLUSIONS

Bone deposition after 1 year of treatment with LC is low (highest concentration: 5.5 microg/g). There is a slow release of lanthanum from its bone deposits 2 years after the discontinuation of the treatment and no association with aluminium-like bone toxicity.

Lumbar Bone Mineral Density in Renal Transplant Patients on Neoral and Tacrolimus: A Four-Year Prospective Study

BACKGROUND

This prospective study was designed to investigate the long-term evolution of bone mineral density (BMD) in kidney transplant recipients.

METHODS

In 86 patients with functioning grafts, 65 on tacrolimus-based immunosuppression and 21 on cyclosporine-based immunosuppression, laboratory parameters and BMD measurements in lumbar spine (L2-L4) and femoral neck (FN) were performed by DEXA in the first month after transplantation (baseline) and yearly thereafter up to the fourth year.

RESULTS

BMD did not change at 12 months in lumbar spine nor in the FN. Detailed analysis identified three patterns of BMD in lumbar spine at 12 months: BMD remained stable in 27 patients (31.4%), decreased >2% in 31 (36.0%) and increased >2% in 28 (32.6%). Patients with no change or gain presented a parallel increase of BMD in FN (P<0.001 in both groups). On multivariate analysis, the variables associated with no change or lumbar BMD loss were total prednisone dose in grams at 12 months (OR 1.402; 95% CI 1.038-1.893; P=0.028), calcitriol levels at 12 months (OR 0.936; 95% CI 0.892-0.982; P=0.007) and lumbar BMD at baseline (OR 1.006; 95% CI 1.002-1.010; P=0.002). Late treatment with calcium supplements and calcitriol did not improve osteopenia.

CONCLUSIONS

One third of patients had bone loss mainly during the first year of follow-up. Bone loss was associated to higher baseline BMD, high steroid dose, and lower calcitriol levels at 1 year. Late administration of calcitriol and calcium supplements did not improve posttransplant osteopenia. More than 50% of patients were osteopenic 4 years after transplantation.

Management of the well renal transplant recipient: outpatient surveillance and treatment recommendations

Although renal transplantation offers survival and quality of life advantages as a renal replacement therapy, a substantial proportion of transplant recipients develop worsening of preexisting medical diseases or new complications, including sequelae of rejection, new onset diabetes after transplantation (NODAT), hyperlipidemia, opportunistic infections, cancer, and other systemic diseases secondary to immunosuppression. Management of these problems can be a complex endeavor due to medication interactions that often affect immunosuppression levels. However, successful management of the chronic medical problems associated with renal transplantation can prolong the life span of the graft and the patient.

Improvement of adynamic bone disease after renal transplantation

Low bone remodeling and relatively low serum parathyroid hormone (PTH) levels characterize adynamic bone disease (ABD). The impact of renal transplantation (RT) on the course of ABD is unknown. We studied prospectively 13 patients with biopsy-proven ABD after RT. Bone histomorphometry and bone mineral density (BMD) measurements were performed in the 1st and 12th months after RT. Serum PTH, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and osteocalcin were measured regularly throughout the study. Serum PTH levels were slightly elevated at transplantation, normalized at the end of the third month and remained stable thereafter. Bone biopsies performed in the first month after RT revealed low bone turnover in all patients, with positive bone aluminum staining in 5. In the 12th month, second biopsies were performed on 12 patients. Bone histomorphometric dynamic parameters improved in 9 and were completely normalized in 6, whereas no bone mineralization was detected in 3 of these 12 patients. At 12 months post-RT, no bone aluminum was detected in any patient. We also found a decrease in lumbar BMD and an increase in femoral BMD. Patients suffering from ABD, even those with a reduction in PTH levels, may present partial or complete recovery of bone turnover after successful renal transplantation. However, it is not possible to positively identify the mechanisms responsible for the improvement. Identifying these mechanisms should lead to a better understanding of the physiopathology of ABD and to the development of more effective treatments.

Bone disease after kidney transplantation

Advances in immunosuppressive therapy have allowed for enhanced allograft survival in kidney transplantation. With this increasing success of transplantation, however, has come a greater appreciation of subsequent complications, such as bone and mineral disease. In patients with chronic kidney disease who are awaiting transplantation, disorders in mineral metabolism and renal osteodystrophy are an essentially universal finding, and several different pathophysiologic mechanisms are believed to contribute to the development of these disorders.